The current emphasis in dental practice is prevention. Accordingly, this project has as its major objective for current and near-future work the development of improved materials for preventive dentistry. One promising approach involves the sealing of developmental pits and fissures of teeth with a hardenable resin. The success of this procedure depends upon the stability of adhesive bonding between the polymer and the enamel surface, so that the obturating material will remain in place indefinitely, preventing carious attack in the otherwise vulnerable tooth defect. A degree of adhesion has been achieved by the etching of the enamel, allowing the "sealant" resin to bond by what seems to be a geometrical penetration and interlocking with microscopic surface asperities. This project will evaluate the contention that further improvement in the reliability of the bonding can be achieved with the additional use of chemical coupling agents, some of which have shown promise in preliminary evaluations; new coupling agents will be synthesized and evaluated.